Boats, when not sailing, are typically anchored to the sea floor or moored to a heavy weight on the sea floor, or secured to a dock. In the case of anchoring or mooring there must be slack in the anchor line or mooring line to accommodate tidal motion which raises and lowers the boat relative to the sea floor and to avoid upward forces that could dislodge the anchor or mooring. This slack necessitates that the boat have room to move without colliding into other boats. On the other hand, a boat may be secured to a dock that is not itself subject to tidal motion. It is not desirable to attach the boat to the dock with a slack rope, since that will both allow the boat to take up more space at the dock and to slam into the dock in response to shifting wind and currents. Unless the lines securing the boat to the dock are constantly adjusted to maintain the boat in its safely docked position, the mooring lines will become too loose or too tight with the changing tides, moving the boat around and causing damage as the boat floats into the dock. It is necessary therefore to arrange that as the tide rises and falls the ropes securing the boat to the dock take up their slack in the rope. This has been accomplished in the past by a system of pulleys and weights. That system, however, suffers from the drawback that it requires the boat to carry the weights needed for tying to the dock. Those weights must be heavy enough to provide a tension in the line great enough to restrain the boat. Carrying such weights is a significant inconvenience, especially in a small boat
Thus, it is desirable to provide a lightweight, compact weight and pulley system that automatically adjusts mooring lines to keep floating objects in place against a dock or seawall to accommodate changing water levels.
U.S. Pat. No. 2,440,972 discloses a mooring device using a rope attached to weight to compensate for tidal motion. U.S. Pat. No. 3,060,884 discloses a boat moored to a floating dock where both the dock and the boat are moored with weight that compensate for tidal motion. U.S. Pat. No. 4,357,009 shows a weight bag which is water filled. None of these references suggest the combination of water filled weight bags with mooring systems.